This plugin allows provisioning of blogs on a WordPress multi-site installation from external packages and billing systems. It adds an API to WordPress that allows the external system to call WordPress to create, suspend, unsuspend and terminate blogs on a WordPress multi-site installation.
A commercial WHMCS addon is currently available for a recurring fee. This allows you to set up a product in WHMCS which will automatically provision WordPress blogs for your customers. It works just like a WHMCS server addon.